1. Technical Field
The present invention relates to a method of processing an object using a laser, and in particular, to a method of multi-processing an object using a polygon mirror that can optimize processing parameters according to properties of an object to be processed and processing purposes.
2. Related Art
In order to form components with various materials, such as wafers, metals, and plastics, processing procedures, such as cutting and grooving, are generally needed. For example, after a semiconductor manufacturing process is completed, cutting is performed to cut a plurality of chips formed on a wafer into individual chips is performed. The wafer cutting process is important because it affects the quality and productivity during a subsequent process. At present, a mechanical sawing method that uses a diamond blade is generally used.
However, since the semiconductor wafer is reduced in thickness, for example, to 150 μm or less, and various materials, such as low-dielectric-constant materials, are used, there is a problem in using the mechanical sawing method in that chipping occurs and the die strength is weakened. Accordingly, new cutting methods have been considered. Of these, a cutting method using a laser is being studied as a substitute for the mechanical sawing method.
Meanwhile, an object to be processed with a laser may have a single layer or a plurality of layers. If an object having a plurality of layers is processed on the same processing condition without considering different characteristics of the plurality of layers, swelling or explosion may occur at the boundary between the layers.
That is, since the layers have different optical, physical, and chemical characteristics, the object should be processed according to processing parameters for the individual layers. However, in the existing laser processing method, since a one-pass mode is used, cracks may occur at the boundary between the layers, and in the worst case, the cracks may spread to the chip region, which may result in deterioration in the yield. In addition, due to a large influence by the HAZ (Heat Effected Zone), the die strength may be decreased.